Reducing vehicular congestion at an interestion

ABSTRACT

To control vehicular congestion at intersections, a method includes detecting a group of two or more vehicles stopped at an intersection regulated by a traffic light, where for each of the vehicles in the group, movement through the intersection in response to a change in a state of the traffic light is affected by movement of at least one other vehicle in the group. The method further includes determining a time when the state of the traffic light changes to allow the group of vehicles to start moving through the intersection, determining acceleration parameters for a certain vehicle in the group in view of potential and/or actual movement of the other vehicles in the group through the intersection, and providing guidance to a device operated by a driver of the certain vehicle regarding the determined acceleration parameters, in accordance with the determined time.

FIELD OF THE DISCLOSURE

The present disclosure relates to navigation applications and, inparticular, to providing guidance to vehicles or devices operating invehicles stopped at an intersection.

BACKGROUND

Today, digital maps of geographic areas and step-by-step directions fornavigating through geographic areas by driving, walking, bicycling, orriding on public transport can be provided on numerous electronicdevices such as personal computers, tablets, mobile phones, navigatorsprovided as special-purpose devices or embedded into head units ofvehicles, etc. The digital maps and/or navigation directions can beprovided via special-purpose mapping applications or “apps,” forexample. Typical driving navigation directions advise drivers to maketurns on certain streets, drive straight for certain distances, mergeonto certain roads, etc.

When going through intersections (or “crossroads”) or generally anytraffic lights or other road junctions, which are known to be one of themajor sources of traffic congestion, drivers typically rely on theirexperience to decide when and how fast they should accelerate. Theinformation available to drivers generally is limited to what they seein front of them and behind them in the rear-view mirror. As a result,many drivers leave more space than necessary between their vehicles andthe vehicles directly in front. Moreover, vehicles accelerate atdifferent rates due to the differences in torque. One result ofsub-optimal human decisions and the differences in vehicle capability isthat fewer vehicles move through a typical intersection per unit of timethan possible. For example, a certain traffic light can display greenfor 90 seconds and allow approximately 300 vehicles to pass through theintersection at a normal speed, but only 200 vehicles may pass throughthe intersection during a typical green phase.

SUMMARY

One example embodiment of the techniques of this disclosure is a methodfor controlling vehicular congestion at intersections. The methodcomprises detecting, by one or more processors, a group of two or morevehicles stopped at an intersection regulated by a traffic light, suchthat for each of the vehicles in the group, movement through theintersection in response to a change in a state of the traffic light isaffected by movement of at least one other vehicle in the group. Themethod further comprises determining, by the one or more processors, atime when the state of the traffic light changes to allow the group ofvehicles to start moving through the intersection, determining, by theone or more processors, acceleration parameters for a certain vehicle inthe group in view of potential and/or actual movement of the othervehicles in the group through the intersection, and providing, by theone or more processors, guidance to a device operated by a driver of thecertain vehicle regarding the determined acceleration parameters, inaccordance with the determined time.

Another example embodiment of the techniques of this disclosure is aportable computing device comprising one or more processors, ashort-range communication interface to communicatively couple theportable computing device to a vehicle, a long-range communicationinterface to communicatively couple the portable computing device to avehicle, and a non-transitory computer-readable medium storinginstructions. The instructions, when executed by the one or moreprocessors, cause the portable computing device to execute the methodabove.

Yet another example embodiment of the techniques of this disclosure is anetwork server comprising one or more computing devices and anon-transitory computer-readable medium storing instructions. Theinstructions, when executed by the one or more computing devices, causethe network server to execute the method above.

Still another example embodiment of the techniques of this disclosure isa computing system comprising one or more processors and anon-transitory computer-readable memory storing instructions. Whenexecuted by the one or more processors, the instructions cause thecomputing system to detect a group of two or more vehicles stopped at anintersection regulated by a traffic light, such that for each of thevehicles in the group, movement through the intersection in response toa change in a state of the traffic light is affected by movement of atleast one other vehicle in the group; determine a time when the state ofthe traffic light changes to allow the group of vehicles to start movingthrough the intersection; determine acceleration parameters for acertain vehicle in the group in view of potential and/or actual movementof the other vehicles in the group through the intersection; and provideguidance to a device operated by a driver of the certain vehicleregarding the determined acceleration parameters, in accordance with thedetermined time.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of an example system in which techniques forreducing congestion can be implemented;

FIG. 2 is a flow diagram of an example method for identifying a group(or “cluster”) of vehicles at an intersection for coordinated guidancethrough the intersection, which can be implemented in the system of FIG.1;

FIG. 3 is a diagram of an example scenario in which the system of FIG. 1can identify a cluster of vehicles for coordinated guidance through anintersection;

FIG. 4 is a diagram of an example scenario in which the system of FIG. 1can identify several clusters of vehicles for coordinated guidancethrough an intersection;

FIG. 5 is a diagram of another example scenario in which the system ofFIG. 1 can identify a cluster of vehicles for coordinated guidancethrough an intersection;

FIG. 6 is a flow diagram of an example method for guiding a cluster ofvehicles through the intersection, which can be implemented in thesystem of FIG. 1;

FIG. 7 is a diagram of an example scenario in which the system of FIG. 1can guide several clusters of vehicles through an intersection; and

FIG. 8 illustrates an example timeline for providing guidance tovehicles being guided through an intersection.

DETAILED DESCRIPTION Overview

Generally speaking, a congestion control system of this disclosurecoordinates acceleration between vehicles at a traffic light so that thevehicles travel through the intersection efficiently and safely. Thesystem thus improves throughput of traffic at an intersection, which inturn allows vehicles to reach their destinations faster and with lowerenergy consumption and/or vehicle emissions. To synchronizeacceleration, the system can determine which vehicles can define a group(or cluster) and provide guidance to smartphones or other suitablecomputing devices operating in these vehicles, or directly to thevehicles in some cases.

When multiple autonomous, or “self-driving,” vehicles are stopped at anintersection, control units implemented in these autonomous vehicles canexchange messages using a suitable wireless communication standard toform an ad hoc cluster of autonomous vehicles. The control units thencan synchronize movement through the intersection to accelerate at aparticular time at the maximum safe rate so as to maintain the shortestsafe distance between adjacent vehicles in the cluster. A congestioncontrol system thus can control the movement of each autonomous vehiclein view of the movement of the other autonomous vehicles in the cluster.

Movement of semi-autonomous vehicles, which implement such technologiesas adaptive cruise control for example, can be controlled in a similarmanner. A typical semi-autonomous vehicle can automatically adjust itsspeed to maintain a certain safe separation from the vehicle directlyahead. In this case, a congestion control system can be implemented inthe control units of the semi-autonomous vehicles in the cluster or in anetwork device operating outside the cluster to control acceleration anddeceleration of the semi-autonomous vehicles through an intersection.Once the semi-autonomous vehicles reach a certain speed or detect anychange in the surroundings (e.g., the vehicle in front turns on itsright turn signal or “blinker”), the congestion control system cannotify the corresponding drivers that they should take back control ofthe vehicles.

However, even as various types of autonomous and semi-autonomousvehicles are being tested and deployed today, many drivers continue tocontrol their vehicles manually. A congestion control system in thiscase can generate navigation directions related to the timing and rateof acceleration at an intersection, and provide these navigationdirections to devices operating in the vehicles. The congestion controlsystem in these cases does not rely on the ability of a vehicle toautomatically adjust its speed.

In one example implementation, the congestion control system of thisdisclosure detects when multiple vehicles approach an intersection oralready have reached the intersection, from a certain direction. Thedetection can be based on sensors operating in the vehicles (cameras,radars, lidars, etc.), sensors operating as components of an urbaninfrastructure (e.g., cameras mounted on traffic lights), camerasmounted in low-flying drones, cameras mounted in satellites, etc. Thecongestion control system then organizes at least two of the vehiclesinto a cluster. The cluster in some cases is only conceptual, asdiscussed below, and the vehicles or the portable devices operating inthese vehicles are not always informed of being organized into acluster. For example, the congestion control system can organizevehicles in a left-only lane into one cluster, vehicles in the rightlane headed straight c into another cluster, etc. The congestion controlsystem in some cases can infer the “intent” of a vehicle from navigationdirections provided to a portable device operating in this vehicle via acorresponding software application, or from the turn signal currentlyactivated in the vehicle.

Once the congestion control system identifies a cluster of vehicles, thecongestion control system determines, for a certain vehicle in thecluster, suitable acceleration parameters in view of the potential oractual movement of the other vehicles in the cluster. The congestioncontrol system in some cases can use additional signals to determinethese parameters, e.g., types of the vehicles in the cluster, thecurrent weather conditions, the current lighting conditions. Thecongestion control system then provides this information to the vehiclein any suitable format or to a portable device operating in the vehiclein the form of text or audio instructions. The acceleration parameterscan specify the time of acceleration and, in some implementations, alsothe rate of acceleration. The congestion control system can determinethese acceleration parameters so as to cause the vehicles in the clusterto reach a certain speed more quickly and/or in a moreenvironment-friendly manner, all the while maintaining a safe distancebetween the vehicles.

In one example scenario, a user of a navigation service receivesstep-by-step driving directions, including real-time updates, via asoftware application running on a smartphone while the user is driving.When the user's vehicle is stopped at an intersection, the user may seeonly the car in front and, in the rear-view mirror, only one car behind.On the other hand, the congestion control system determines whichvehicles will affect the timing and the rate of acceleration of theuser's vehicle when the traffic light changes. These vehicles can definean ad hoc cluster and can include vehicles separated from the user'svehicle by multiple intervening vehicles. The congestion control systemthen generates an appropriate instruction and provides the instructionto the user via the application running on the smartphone. For example,the instruction may include a countdown to the time the user shouldstart accelerating as well as a warning regarding the safe rate ofacceleration. As another example, the congestion control system canprovide an estimate of when the vehicle in front of the user's vehiclewill start moving.

In another example scenario, more than one user in the ad hoc clusterincluding the user's vehicle operates the software applicationassociated with the navigation service. The congestion control system inthis case coordinates the acceleration of these vehicles. Moreparticularly, the system can first provide acceleration instructions tothe smartphone in the vehicle disposed closer to the intersection, andthen provide acceleration instructions to the smartphone in the vehiclefarther away to the intersection.

Example Computing Environment

Referring to FIG. 1, an example environment 10 in which the techniquesoutlined above can be implemented includes a vehicle 12, a computingdevice 14 operating in the vehicle, and a server 16 that providesmapping and navigation services. The example environment 10 in somecases can include one or more external cameras/sensors 18 that in turncan include one or more cameras, radars, lidars, infrared or thermalimaging devices, etc., or any suitable combination of these devices. Theserver 16 can communicate with the computing device 14 and the one ormore external cameras/sensors 18 via a communication network 20, whichcan be a wide area network such as the Internet.

The vehicle 12 in the scenario of FIG. 1 can be a non-autonomous, i.e.,a conventional, vehicle or a semi-autonomous vehicle. In addition to anengine, a transmission, brakes, etc. 30, the vehicle 12 can be equippedwith sensors such as one or more proximity sensors 32 and one or morecameras 34. A control circuitry 36 can be configured to detect whethervehicles are present within a certain distance immediately ahead of thevehicle 12 and/or immediately behind the vehicle 12, using the proximitysensor(s) 32 and/or the camera(s) 34. In some implementations, thevehicle circuitry 34 also determines the approximate distance to thesevehicles (e.g., 10 feet, 12 feet, 50 feet). The vehicle 12 also caninclude a head unit 38 equipped with input and output devices such as atouchscreen, a speaker, a microphone, etc.

Further, the head unit 38 in one example embodiment is equipped with awireless communication module that supports a Bluetooth™-based wirelesspersonal area network (WPAN) to communicate with proximate electronicdevices such as the computing device 14 for example. The head unit 38also can be configured to measure the signal strength for Bluetoothbeacons transmitted from nearby vehicles to determine approximatedistances to these vehicles.

The computing device 14 can be for example a portable device such as asmartphone, a tablet computer, or a wearable device such as asmartwatch. The computing device 14 alternatively can be aspecial-purpose car navigator or an electronic device embedded in thehead unit of the vehicle 12. In the example implementation of FIG. 1,the computing device 14 includes one or more processing units 40 whichcan include a central processing unit (CPU), a graphics processing unit(GPU), etc. The computing device 14 further includes a non-transitorymemory 42 that can include random access memory (RAM), read-only memory(ROM), flash memory, other types of persistent memory, etc. The memory42 can store instructions that implement an operating system (OS) 52,which can be any suitable mobile or general-purpose operating system,and a navigation application 54. The computing device 14 also caninclude a short-range communication interface 44, a long-rangecommunication interface 46, a camera 48, and a user interface 50.

The short-range communication interface 44 can support communicationsvia a wireless personal area network (WPAN) such as Bluetooth, awireless local area network (WLAN) such as WiFi™, a wired connectionsuch as Universal Serial Bus (USB), etc. The computing device 14 iscoupled to the vehicle 12 via a short-range communication link supportedby the short-range communication interface 44, in the example of FIG. 1.The long-range communication interface 46 can support, for example,cellular communications according to various 3G, 4G, 5G, etc.communication standards and/or wide area network communications such asWiFi. The camera 48 can be any suitable charge-coupled device (CCD) orcomplementary metal-oxide semiconductor (CMOS) camera. In an examplescenario, the computing device 14 is mounted on the dashboard of thevehicle 12 so that the camera 48 faces the road ahead of the vehicle 12,and a software application executing on the computing device 14 detectsan approximate distance to the vehicle immediately ahead of the vehicle12.

In addition to the camera 48, the computing device 14 in variousembodiments can include sensor components or modules such as a globalpositioning system (GPS) module to detect the position of the computingdevice 14, a compass to determine the direction of the computing device14, a gyroscope to determine the rotation and tilt, an accelerometer,etc.

The user interface 50 can include any suitable combination of inputdevices such as a touchscreen, a keyboard, a microphone, etc. and outputdevices such as screens, speakers, etc. In operation, the navigationapplication 54 can receive instructions from the user and providenavigation directions in the form of text, images, videos, vocalizedinstructions, etc. via the user interface 50. The navigation application54 can provide an interactive digital map via the user interface 50. Thenavigation application 52 in some cases can operate in a projected modeand direct some or all of the output to an external device such as thehead unit 38.

The navigation application 54 can receive map data in a raster (e.g.,bitmap) or non-raster (e.g., vector graphics) format from the server 16.In some cases, the map data can be organized into layers, such as abasic layer depicting roads, streets, natural formations, etc., atraffic layer depicting current traffic conditions, a weather layerdepicting current weather conditions, a navigation layer depicting apath to reach a destination, etc. The navigation application 54 canprovide navigation directions as a graphic overlay on a digital map, asa sequence of instructions that include text and/or images, as a set ofvocalization instructions via speakers, or any suitable combinationthereof.

With continued reference to FIG. 1, the server 16 can be operated by aprovider of mapping and navigation services. The server device 16 canprovide map data and navigation data to the computing device 14 andother client devices. The server device 16 can be communicativelycoupled to a database 60 that stores geographic data including map datafor various geographic areas. The map data can be stored in any suitableformat such as vector graphics, rasterized images, text for labels, etc.and organized according to any suitable principle (e.g., square maptiles covering the same amount of area at a certain zoom level). The mapdata can specify the shapes and various properties of geographicfeatures such as roads, buildings, lakes, rivers, parks, etc. The mapdata also can include street-level imagery and photographs taken fromvarious vantage points. Further, map data for a geographic areas caninclude information about brick-at-mortar businesses located at therespective locations within the geographic area: hours of operation,description of products and services, user reviews, etc. The geographicdata in the database 60 also can store data related to roads and lanessuch as indications of which lanes at certain intersections areleft-turn-only lanes, right-turn-only lanes, etc. As discussed below,the system can use road and lane data when defining clusters of vehiclesat intersections.

The server 16 can implement a mapping/navigation module 62 and acongestion controller 64. Each of the modules 62 and 64 can beimplemented as a set of instructions stored in a memory that includesnon-transitory medium such as a hard disk, a flash drive, etc., andexecutable by one or more processors of the server 16.

For simplicity, FIG. 1 illustrates the server device 16 as only oneinstance of a server. However, the server device 16 according to someimplementations includes a group of one or more server devices, eachequipped with one or more processors and capable of operatingindependently of the other server devices. Server devices operating insuch a group can process requests from the client computing device 14individually (e.g., based on availability), in a distributed mannerwhere one operation associated with processing a request is performed onone server device while another operation associated with processing thesame request is performed on another server device, or according to anyother suitable technique. For the purposes of this discussion, the term“server device” may refer to an individual server device or to a groupof two or more server devices.

The one or more external cameras/sensors 18 can operate in any suitablestructure, vehicle, aircraft, etc. For example, the one or more externalcameras/sensors 18 can be installed on traffic lights, light posts,walls of buildings, etc. In other scenarios, the one or more externalcameras/sensors 18 can operate in unmanned aerial vehicles (UAVs) orsatellites. In any case, imagery captured by the one or more externalcameras/sensors 18 can be processed to determine locations of vehicles,spacing between vehicles, types of vehicles (e.g., a car, a van, atruck). This imagery in some cases also can be used to determine thestate of the traffic light.

In some embodiments, the server 16 can receive real-time data related tothe state of traffic lights from a dedicated electronic service. Forexample, a certain municipality may expose an API using which softwaresystems can determine the current state of a selected traffic light, thetime remaining in the current state, the expected duration of the nextstate, etc.

Using the data stored in the database 60, the mapping/navigation module62 can generate routes traversing geographic areas and navigationinstructions to guide drivers along the generated routes. The congestioncontroller 64 can augment these navigation instructions with guidancefor efficiently traversing intersections, as discussed in more detailbelow. In some embodiments, the functionality of the congestioncontroller 64 can be implemented partially or fully in the navigationapplication 54 or multiple instances of the navigation application 54.More particularly, multiple instances of the navigation application 54operating in different respective devices (which in turn are disposed indifferent respective vehicles) can exchange information with each otherto cooperatively determine the acceleration parameters for thecorresponding vehicles.

Guiding Vehicles Through Intersections

Now referring to FIG. 2, an example method 100 for identifying a group(or “cluster”) of vehicles at an intersection for coordinated guidancethrough the intersection can be implemented as a set of instructionsexecutable by one or more processors. These instructions can be includedin the congestion controller 64, the navigation application 54, orpartially in the congestion controller 64 and partially in thenavigation application 54. Further, the method 100 in some embodimentsis implemented in the head unit 38. For clarity, the method 100 isdiscussed below with reference to a congestion control system that caninclude one or more of: (i) the congestion controller 64, (ii) one ormore instances of the navigation application 54, and (ii) one or moreinstances of the control circuitry 36.

At block 102, the congestion control system detects a vehicle within acertain distance of an intersection. Referring to FIG. 3, for example,each of the vehicles V₁, V₂, and V₃ is within a distance D_(MAX) of anintersection 150 controlled by a traffic light 152. The congestioncontrol system first can determine that the vehicle V₁ is proximate tothe intersection 150.

As one specific example, a portable computing device similar to thedevice 14 of FIG. 1 can operate in the vehicle V₁. An instance of thenavigation application 54 running on the portable device can receive,from a navigation service, a description of a route to a certaindestination along with step-by-step navigation instructions. Thedescription of the route can include locations of intersections. Thepositioning module operating in the vehicle V₁, which can rely on GPS orWiFi signals for example, can determine at some point that the vehicleV₁ is within the distance D_(MAX) of the intersection 150.

Referring back to FIG. 2, the congestion control system at block 104 candetermine that the vehicle has stopped, or is about to stop, at theintersection. To continue with the example above, the portable deviceoperating in the vehicle V₁ can determine that the current speed of thevehicle V₁ is below a certain threshold v_(T) (e.g., 5 mph, 3 mph) usingthe positioning module of the portable device or based on one or moresensors of the vehicle V₁.

The congestion control system also can determine whether the vehicle isstopped at the intersection due to the state of the traffic light. Thecongestion control system can refrain from forming a cluster of vehiclesat the intersection (or form a different type of cluster) if the vehicleis stopped due to traffic congestion or some other reason. In someembodiments, the congestion control system attempts to form a cluster ofvehicles only in response to determining a transition of the trafficlight from red to green. For example, the congestion control system canrely on the dashboard camera of the vehicle with a clear view of thetraffic light to detect the changes in the state of the traffic light.In other embodiments, the congestion control system attempts to form acluster of vehicles in advance of the transition of the traffic lightfrom red to green. As indicated above, the congestion control system canobtain an indication of not only the current state of the traffic lightbut also of when the traffic light will change from red to green.

Next, at block 106, it is determined whether another vehicle can beadded to the cluster. The congestion control system can determine forexample whether there is another vehicle that is traveling in the samedirection and is within the certain distance of the intersection. Insome cases, the congestion control system can impose the additionalrequirement that the other vehicle be in the same lane. In other cases,the congestion control system can determine that lanes from multiplevehicles can be clustered due to lane merging, for example, as discussedwith reference to FIG. 5. Referring again to FIG. 3, the congestioncontrol system can determine that the vehicle V₂ is in the same lane L₂as the vehicle V₁, and that the vehicle V₁ is within the distanceD_(MAX) of the intersection 150.

Another requirement the congestion control system can impose is acertain maximum separation dr between adjacent vehicles in the cluster.The congestion control system can determine that the vehicles V₁ and V₂are separated by a gap of length D₁, and that D₁ is smaller than d_(T).

The congestion control system can approximately measure the gap D₁between the vehicles V₁ and V₂ using sensors internal to these vehiclesor portable devices operating in these vehicles, external to thesevehicles or the portable devices, or any suitable combination of both.As discussed above with reference to FIG. 1, the control circuitry 36embedded in the vehicle can determine approximate distances to othervehicles and/or other objects on the road immediately ahead of thevehicle and immediately behind the vehicle using the proximity sensor(s)32 and/or the camera(s) 34. In another embodiment, the congestioncontrol system can determine the spacing between vehicles in a clusterusing the external cameras/sensors 18. In yet another embodiment, thecongestion control system can use positioning data, such as GPS data forexample, obtained by the portable devices disposed in the vehicles. Moreparticularly, the OS 52 can automatically determine when the computingdevice 14 operates in a vehicle, and users can configure their portabledevices so that during driving, these devices provide positioning data,in an anonymized manner, to the congestion control system for thespecific purpose of determining gaps between vehicles. In anotherembodiment, the portable devices determine approximate distances tonearby portable devices operating in vehicles based on signal strengthmeasurements for Bluetooth or WiFi beacons.

If it determined at block 106 than another vehicle satisfies the one ormore conditions for entry into the cluster, the flow proceeds to block108, where the congestion control system adds this vehicle to thecluster. In the example above, the congestion control system can add thevehicle V₂ to the cluster C₁, so that C₁ becomes {V₁, V₂}. The flow thenreturns to block 106. The congestion control system similarly candetermine that vehicle V₃ is in the same lane L₂ as the vehicle V₁, thatthe vehicle V₃ is within the distance D_(MAX) of the intersection 150,and that the vehicles V₂ and V₃ are separated by gap of length D₁, whereD₁<d_(T). In response to this determination, the congestion controlsystem can add the vehicle V₃ to the cluster C₁, so that C₁ becomes {V₁,V₂, V₃}.

Otherwise, if it determined at block 106 that no other vehicle satisfiesthe one or more conditions for being added to the cluster, the flowproceeds to block 110, where the formation of the cluster completes. Thecongestion control system then can begin to control, or at least affect,movement of an individual vehicle in the cluster in view of movement ofthe other vehicles in the cluster. For example, the congestion controlsystem can control the time and the rate of acceleration for the vehicleV₂ in view of the movement of the vehicle V₁, and similarly control thetime and the rate of acceleration for the vehicle V₃ in view of themovement of the vehicle V₂.

The congestion control system thus can form a cluster of vehiclesaccording to the method 100 with or without the vehicles in the clustercommunicating with each other. In some implementations, the vehicles V₁,V₂, and V₃ illustrated in FIG. 3 and/or portable devices operating inthese vehicles can form an ad hoc communication network when thesevehicles are within the distance D_(MAX) of the intersection 150, arestopped or stopping, and are headed in the same direction. The vehiclesto this end can use a WLAN, WPAN, or another suitable communicationscheme. This ad hoc communication network can serve the specific purposeof controlling acceleration and spacing between the vehicles in thecluster at the intersection 150, and the communication network canautomatically dissolve once the vehicles reach a certain minimum speedand clear the intersection or in response to another event as discussedbelow. The congestion control system in this case can operate in adistributed manner in the communication network. In otherimplementations, the congestion control system can identify a clusterand provide guidance to the vehicles without notifying these vehicles ofthe formation of the cluster. The congestion control system in thisembodiment need not rely on any direct communication between thevehicles in the cluster. Moreover, the congestion control system in someembodiments can provide guidance to vehicles based solely on datacollected from outside the cluster, e.g., from the externalcameras/sensors 18, and need not rely on any data reported by thevehicles or portable devices operating in these vehicles.

Further, the congestion control system need not require that eachvehicle in the cluster have the same capability. For example, thevehicle V₁ can be an autonomous vehicle, the vehicle V₂ can be aconventional vehicle in which the driver currently does not operate aportable device at all, and the vehicle V₃ can be a conventional vehiclein which the driver operates a portable device currently executing aninstance of the navigation application 54. The congestion control systemcan provide guidance to the portable device in the vehicle V₃ withrespect to movement through the intersection in view of what thecongestion control system can observe regarding the other vehicles inthe cluster, even if the congestion control system cannot provideguidance to the other vehicles and thus cannot coordinate the movementthrough the intersection between the vehicles in this cluster.

FIG. 4 illustrates another example formation of clusters at anintersection. Vehicles V₄ and V₅ have either come to a complete stop orare moving at a speed below v_(T) in lane L₁. The congestion controlsystem forms a cluster C₂={V₄, V₅} upon determining that every conditionfor forming such a cluster is satisfied. These conditions can includefor example the vehicles being within a certain threshold distance ofthe intersection 150, the traffic light 152 being in the red state, thespacing between the vehicles being within a certain threshold value, andthe vehicles being headed in the same direction. Thus, although vehicleV₆ is also in the lane L₁ and is headed in the same direction, thespacing between the vehicles V₅ and V₆ is too large, and the congestioncontrol system does not include the vehicle V₆ in the cluster C₂.

The congestion control system also can determine that the vehicles inthe cluster C₂ will turn left. The congestion control system can makethis determination based on the turn signals activated in the vehiclesV₄ and V₅ or based on the navigation directions provided to the portabledevices operating in these vehicles, for example. The congestion controlsystem can determine acceleration parameters in view of whether acluster of vehicles will move forward through the intersection, turnright, turn left, or make a U-turn.

FIG. 5 illustrates still another example of forming a cluster ofvehicles at an intersection. In this scenario, the congestion controlsystem forms a cluster C₄ including vehicles V₇, V₈, and V₉, even thoughthe vehicle V₈ is in a different lane than the vehicles V₇ and V₉. Thecongestion control system determines that the vehicles V₇, V₈, and V₉are headed in the same direction, that there is only one lane availablefor movement in this direction after the intersection 150, and that thevehicles V₇, V₈, and V₉ thus will need to merge. The congestion controlsystem can adjust the acceleration parameters for the vehicles in thecluster C₄ in view of the anticipated merge maneuver.

Next, FIG. 6 illustrates an example method 200 for guiding a cluster ofvehicles through an intersection. Similar to the method 100, the method200 can be implemented as a set of instructions executable by one ormore processors, and these instructions can operate in the congestioncontrol system.

The method 200 begins at block 202, where a cluster of vehicles isidentified. For example, the cluster can be initially identified inaccordance with the method 100 discussed above. The make-up of a clusterhowever need not stay the same during the period when the congestioncontrol system guides vehicles through an intersection. For example,vehicles can enter and leave lanes, turn left or right, etc. Thecongestion control system can support dynamic clustering to account forthese situations. As illustrated in FIG. 7, after the traffic light 152transitions from red to green and the congestion control system beginsguiding the cluster C₁ through the intersection 150, the vehicle V₁changes lanes while the vehicle V₂ following immediately behind remainsin the original lane. The congestion control system accordingly canmodify the cluster C₁ so that the modified cluster C′₁ includes onlyvehicles V₂ and V₃.

Referring again to FIG. 6, one or more acceleration parameters for thevehicles in the cluster are determined at block 204. The accelerationparameters in general can include one or more times when the vehicleshould modify its speed (e.g., start accelerating at time t₀, decreasethe rate of acceleration at the speed at time t₁), the rate ofacceleration (e.g., 3 m/s², 4 m/s²), etc. As discussed below, thecongestion control system in some cases can map these numeric values toinstructions with qualitative terms (e.g., “faster,” “slower”) a drivercan follow more easily.

In one embodiment, the parameters determined at block 204 include onlythe time when the vehicle should start to accelerate, for each of thevehicles in the cluster. The congestion control system can operateaccording to this embodiment when the vehicles in the cluster do nothave any autonomous or semi-autonomous capability: the congestioncontrol system can provide the timing information to the portabledevices operated in the corresponding vehicles, and the drivers canaccelerate in accordance with their abilities and preferences. Theprecise timing of acceleration can provide an improvement in trafficthroughput at the intersection, even if this improvement is lesssignificant than the improvement due to controlling both the timing andthe rate of acceleration.

Referring back to FIG. 4, for example, the cluster C₁ includes thevehicles V₁ at the head of the queue, the vehicle V₂ immediately behindthe vehicle V₁, and the vehicle V₃ immediately behind the vehicle V₂.The congestion control system can determine that the cluster C₁ canefficiently move through the intersection if the vehicles V₁, V₂, and V₃accelerate at times t₁, t₂, and t₃, respectively. As a more specificexample, the congestion control system can determine that the vehicle V₁should accelerate immediately in response to the traffic light 152changing to green, that the vehicle will be at a safe distance d_(safe)from the vehicle V₂ after t₂ amount of time, etc. The congestion controlsystem generally can implement any suitable analytical or numericaltechnique for estimating the distance a vehicle is expected to coverwith a certain acceleration. In another scenario, however, thecongestion control system can determine that all vehicles in the clustershould start accelerating at the same time to move through theintersection more efficiently.

In some embodiments, the parameters determined at block 204 include thetime when the vehicle should start to accelerate as well as the ratewhen the vehicle should accelerate, for each of the vehicles in thecluster. According to one such embodiment, the congestion control systemprovides the rate of acceleration parameter along with the timingparameter to a semi-autonomous vehicle capable of accelerating at arelatively precise rate for a relatively precise amount of time (e.g.,“accelerate at 2 m/s² at time t₀=13:58:59.22, for 1.9 seconds”).According to another embodiment, the congestion control system providesthe rate of acceleration parameter along with the timing parameter to aconventional vehicle, but maps the numeric values and some quantitativeinstructions to qualitative instructions the driver can understand,e.g., “accelerate slowly for about two seconds,” “accelerate freelyuntil you reach 20 mph.”

The congestion control system can determine the one or more accelerationparameters in view of the capability of individual vehicles, in someembodiments. For the example cluster C₁, the congestion control systemcan determine that the vehicle V₁ is a sedan and should acceleraterelatively quickly, the vehicle V₂ is a truck and should acceleraterelatively slowly, etc. To this end, the congestion controller 64 oranother component of the congestion control system in one embodimentprocesses the imagery captured by the external cameras/sensors 18 andruns a classifier to determine the types of vehicles. In anotherembodiment, the congestion control system obtains more precise vehicledata (e.g., make, model) from the vehicles in the cluster C₁ and/or theportable devices operating in these vehicles, provided that the userconfigured the corresponding software applications to provide this datato the congestion control system for the purpose of executing the method200 or a similar method.

Further, the congestion control system can adjust the one or moreacceleration parameters for a certain vehicle in view of what thevehicle, or the driver of the vehicle, cannot see due to the limitedvision from the vantage point of the vehicle. In the example scenario ofFIG. 4, the driver of the vehicle V₃ most likely cannot see the vehicleV₁ due to the large size of the truck V₂. The congestion control systemin some cases may determine that the vehicle V₁ may not be able toaccelerate quickly (or is not accelerating quickly, after the initialguidance has been provided), and accordingly adjust the one or moreacceleration parameters downward for the vehicle V₃. In this manner, inaddition to improving the efficiency of moving multiple vehicles throughan intersection, the congestion control system can provide warnings todrivers regarding slower-than-expected acceleration and thereby improvesafety.

Still further, the congestion control system can adjust the one or moreacceleration parameters for a certain vehicle depending on how many ofthe other vehicles in the cluster, or the corresponding portabledevices, currently participate in the coordinated movement through theintersection. The congestion control system can project less efficientacceleration for vehicles in the cluster that are not currentlyreceiving guidance from the congestion control system.

The congestion control system in some cases can adjust the one or moreacceleration parameters in view of the weather conditions and/orlighting conditions. More particularly, the congestion control systemmay determine that the vehicles in the cluster should accelerate moreslowly if the ambient conditions include rain, snow, or fog. Thecongestion control system can receive an indication of the currentweather conditions at the intersection from a real-time weather serviceor from the sensors in the vehicles or the portable devices. Thecongestion control system may determine that the vehicles in the clustershould accelerate more slowly at certain hours at night.

The congestion control system also can adjust the one or moreacceleration parameters upon determining that the cluster or a portionof the cluster will make a turn. The guidance the congestion controlsystem provides in these cases can include slower acceleration. Thecongestion control system can indicate that even lower acceleration isappropriate upon determining that the cluster or a portion of thecluster plans a U-turn. For example, the congestion control system canselect the one or more acceleration parameters so that none of thevehicles in the cluster exceeds a certain threshold speed. The thresholdspeed for the U-turn scenario can have one value, the threshold speedfor the left or right turn scenario can have another, higher value, andthe threshold speed for the driving straight scenario can have an evenhigher value. The congestion control system can select and adjust thesevalues in view of the speed limit near the intersection, the weatherconditions, the lighting conditions, etc.

With continued reference to FIG. 6, at block 206, guidance is generatedfor the one or more vehicles in the cluster. As discussed above, thecongestion control system can provide semi-autonomous vehicles withinstructions that are relatively precise with respect to the time andrate of acceleration.

On the other hand, the congestion control system can generate lessprecise guidance to a portable device operating in a conventionalvehicle. The guidance provided to a conventional vehicle can includetextual instructions that can be inserted into the sequence ofstep-by-step driving directions, imagery, vocalized instructions, etc.In an example embodiment, the congestion controller 64 augments thestep-by-step driving directions generated by the navigation module 62,so that the example sequence includes the vocalized instructions “HeadNorth on Oak St.,” “turn right on Lake St.,” “prepare to startaccelerating in 2 seconds,” “accelerate freely to 15 mph,” “continuedriving on Lake St. for two miles,” etc.

At block 208, the congestion control system can provide the generatedguidance to one, several, or all vehicles in the cluster, at therespective times. These times can be the same or different, depending onwhat the congestion control system previously determined would result ina more efficient scheme. Not every vehicle in a cluster may beconfigured to receive guidance from the congestion control system, asdiscussed above. Further, the congestion control system can provideguidance to different vehicles in different formats, e.g., in one formatat one degree of precision for a semi-autonomous vehicle and in adifferent format at a different degree of precision to a conventionalvehicle in the cluster.

The congestion control system can determine whether the vehicle hasreached a target speed at block 210. To this end, the congestion controlsystem can use the sensors of the vehicle, the portable device, orimagery collected via a camera external to the cluster. If the vehiclehas reached the target speed, the flow can proceed to block 216, wherethe congestion control system can dissolve the cluster. Otherwise, theflow proceeds to block 212. In another scenario, the congestion controlsystem detects a change in the surroundings or a change related to thecluster of vehicles. Examples of such changes include a vehicle in thecluster activating its turn signal, failure of a vehicle in the clusterto accelerate, a dog running out on the road in front of or near avehicle in the cluster, etc. The congestion control system in this caseproceeds to block 216 to dissolve the cluster or divide the cluster intotwo or more smaller clusters.

In one example scenario in which the congestion control system dividesthe cluster, the congestion control system initially forms a cluster often vehicles and guides the cluster through an intersection. The driverof the fifth vehicle in the cluster intends to make a right turn into agas station 1000 feet past the intersection. The driver of this vehicleturns on the right turn signal after driving 500 feet past theintersection. In response to detecting that the right turn signal in thefifth vehicle has been activated, the congestion control system canautomatically divide the cluster into three clusters: a first clusterwith the four vehicles in front of the fifth vehicle preparing for theturn, a second cluster including only the fifth vehicle preparing forthe turn, and a third cluster including the last five vehicles of theoriginal cluster.

At block 212, the congestion control system can monitor the movement ofthe cluster at block 212. In particular, the congestion control systemcan ensure that the vehicles maintain a safe distance, that none of thevehicles accelerates too quickly or too slowly, that the make-up of thecluster remains the same, etc. For those vehicles being actively guided,the congestion control system can provide updated guidance at block 214.For example, the congestion control system can generate a vocalizedinstruction “slow down” or “do not accelerate to a speed above 20 mph.”The flow then returns to block 210.

For further clarity, FIG. 8 illustrates an example timeline 300 forproviding guidance to a portable device operating in a vehicle. In thisexample scenario, each of the vehicles in the cluster is capable ofreceiving guidance, in the same or different formats, from thecongestion control system. The event 302 can include advance guidance tovehicles regarding the traffic light. In one scenario, the advanceguidance can include an indication of how much time remains until thetraffic light changes to green. More generally, the advance guidance caninclude any potentially useful information such as an estimated amountof time it will take the vehicle to move through the intersection, anindication of how many vehicles are queued up at the intersection infront of the vehicle, etc.

The congestion control system then can notify each of the vehicles inthe cluster of the traffic light change (event 304) and cause thevehicles to start accelerating (events 306A, 306B, etc.). In onescenario, each of the events 306A, 306B, etc. occurs at the same time,at the same time as or shortly after the event 304. In another scenario,the congestion control system spreads out in time the events 306 so asto account for the differences in the ability of the vehicles in thecluster to accelerate. For example, the truck in FIG. 2 may acceleratesignificantly slower than a lighter vehicle, and the congestion controlsystem can delay the instruction to start accelerating for the vehiclepositioned behind the truck.

The congestion control system can monitor the movement of the clusterthrough the intersection and, in some cases, provide updates to thecorresponding vehicles and/or portable devices operating in thesevehicles (events 308). As discussed above, the make-up of a cluster canchange, some vehicle can accelerate faster or slower than expected, etc.When the desired speed is reached, or when the congestion control systemdetermines that the cluster should be dissolved for another reason asdiscussed above (event 310), the congestion control system can stopproviding guidance to the vehicles and, in some cases, notify thevehicles of the termination of this procedure.

Referring generally to FIGS. 1-8, it is noted that the term“intersection” can apply to any junction between roads such as afour-way road junction as shown in the drawings, a three-way junction(such as t-junction or a y-junction), a junction of more than fourroads, a staggered junction, or a roundabout (also known as a trafficcircle). These junctions can be controlled by traffic lights, stopsigns, yield signs, or other types of road signs. The congestion controlsystem can determine the type of an intersection and adjust theacceleration parameters accordingly. For example, for a traffic circle,the congestion control system can identify a cluster that includesvehicles that approached the traffic circle from different directionsand currently stopped at different entry points of the traffic circle.The congestion control system can guide the vehicles in such a clusterto start accelerating at the same time to enter the traffic circle atthe same time at different locations.

ADDITIONAL CONSIDERATIONS

The following additional considerations apply to the foregoingdiscussion. Throughout this specification, plural instances mayimplement components, operations, or structures described as a singleinstance. Although individual operations of one or more methods areillustrated and described as separate operations, one or more of theindividual operations may be performed concurrently, and nothingrequires that the operations be performed in the order illustrated.Structures and functionality presented as separate components in exampleconfigurations may be implemented as a combined structure or component.Similarly, structures and functionality presented as a single componentmay be implemented as separate components. These and other variations,modifications, additions, and improvements fall within the scope of thesubject matter of the present disclosure.

Additionally, certain embodiments are described herein as includinglogic or a number of components, modules, or mechanisms. Modules mayconstitute either software modules (e.g., code stored on amachine-readable medium) or hardware modules. A hardware module istangible unit capable of performing certain operations and may beconfigured or arranged in a certain manner. In example embodiments, oneor more computer systems (e.g., a standalone, client or server computersystem) or one or more hardware modules of a computer system (e.g., aprocessor or a group of processors) may be configured by software (e.g.,an application or application portion) as a hardware module thatoperates to perform certain operations as described herein.

In various embodiments, a hardware module may comprise dedicatedcircuitry or logic that is permanently configured (e.g., as aspecial-purpose processor, such as a field programmable gate array(FPGA) or an application-specific integrated circuit (ASIC)) to performcertain operations. A hardware module may also comprise programmablelogic or circuitry (e.g., as encompassed within a general-purposeprocessor or other programmable processor) that is temporarilyconfigured by software to perform certain operations. It will beappreciated that the decision to implement a hardware modulemechanically, in dedicated and permanently configured circuitry, or intemporarily configured circuitry (e.g., configured by software) may bedriven by cost and time considerations.

Accordingly, the term hardware should be understood to encompass atangible entity, be that an entity that is physically constructed,permanently configured (e.g., hardwired), or temporarily configured(e.g., programmed) to operate in a certain manner or to perform certainoperations described herein. As used herein “hardware-implementedmodule” refers to a hardware module. Considering embodiments in whichhardware modules are temporarily configured (e.g., programmed), each ofthe hardware modules need not be configured or instantiated at any oneinstance in time. For example, where the hardware modules comprise ageneral-purpose processor configured using software, the general-purposeprocessor may be configured as respective different hardware modules atdifferent times. Software may accordingly configured on a processor, forexample, to constitute a particular hardware module at one instance oftime and to constitute a different hardware module at a differentinstance of time.

Hardware modules can provide information to, and receive informationfrom, other hardware. Accordingly, the described hardware modules may beregarded as being communicatively coupled. Where multiple of suchhardware modules exist contemporaneously, communications may be achievedthrough signal transmission (e.g., over appropriate circuits and buses)that connect the hardware modules. In embodiments in which multiplehardware modules are configured or instantiated at different times,communications between such hardware modules may be achieved, forexample, through the storage and retrieval of information in memorystructures to which the multiple hardware modules have access. Forexample, one hardware module may perform an operation and store theoutput of that operation in a memory device to which it iscommunicatively coupled. A further hardware module may then, at a latertime, access the memory device to retrieve and process the storedoutput. Hardware modules may also initiate communications with input oroutput devices, and can operate on a resource (e.g., a collection ofinformation).

The methods 100 and 200 may include one or more function blocks,modules, individual functions or routines in the form of tangiblecomputer-executable instructions that are stored in a non-transitorycomputer-readable storage medium and executed using a processor of acomputing device (e.g., a server, a personal computer, a smart phone, atablet computer, a smart watch, a mobile computing device, or otherpersonal computing device, as described herein). The methods 100 and 200may be included as part of any backend server (e.g., a map data server,a navigation server, or any other type of server computing device, asdescribed herein), portable device modules of the example environment,for example, or as part of a module that is external to such anenvironment. Though the figures may be described with reference to theother figures for ease of explanation, the methods 100 and 200 can beutilized with other objects and user interfaces. Furthermore, althoughthe explanation above describes steps of the methods 100 and 200 beingperformed by specific devices, this is done for illustration purposesonly.

The various operations of example methods described herein may beperformed, at least partially, by one or more processors that aretemporarily configured (e.g., by software) or permanently configured toperform the relevant operations. Whether temporarily or permanentlyconfigured, such processors may constitute processor-implemented modulesthat operate to perform one or more operations or functions. The modulesreferred to herein may, in some example embodiments, compriseprocessor-implemented modules.

Similarly, the methods or routines described herein may be at leastpartially processor-implemented. For example, at least some of theoperations of a method may be performed by one or more processors orprocessor-implemented hardware modules. The performance of certain ofthe operations may be distributed among the one or more processors, notonly residing within a single machine, but deployed across a number ofmachines. In some example embodiments, the processor or processors maybe located in a single location (e.g., within a home environment, anoffice environment or as a server farm), while in other embodiments theprocessors may be distributed across a number of locations.

The one or more processors may also operate to support performance ofthe relevant operations in a “cloud computing” environment or as anSaaS. For example, as indicated above, at least some of the operationsmay be performed by a group of computers (as examples of machinesincluding processors), these operations being accessible via a network(e.g., the Internet) and via one or more appropriate interfaces (e.g.,APIs).

Still further, the figures depict some embodiments of the exampleenvironment for purposes of illustration only. One skilled in the artwill readily recognize from the following discussion that alternativeembodiments of the structures and methods illustrated herein may beemployed without departing from the principles described herein.

Upon reading this disclosure, those of skill in the art will appreciatestill additional alternative structural and functional designs forreducing congestion at intersections through the disclosed principlesherein. Thus, while particular embodiments and applications have beenillustrated and described, it is to be understood that the disclosedembodiments are not limited to the precise construction and componentsdisclosed herein. Various modifications, changes and variations, whichwill be apparent to those skilled in the art, may be made in thearrangement, operation and details of the method and apparatus disclosedherein without departing from the spirit and scope defined in theappended claims.

1. A method for controlling vehicular congestion at intersections, themethod comprising: detecting, by one or more processors, a group of twoor more vehicles stopped at an intersection regulated by a trafficlight, wherein for each of the vehicles in the group, movement throughthe intersection in response to a change in a state of the traffic lightis affected by movement of at least one other vehicle in the group;determining, by the one or more processors, a time when the state of thetraffic light changes to allow the group of vehicles to start movingthrough the intersection; determining, by the one or more processors,one or more acceleration parameters for a certain vehicle in the groupin view of potential and/or actual movement of the other vehicles in thegroup through the intersection; and providing, by the one or moreprocessors, guidance to a device operated by a driver of the certainvehicle regarding the determined one or more acceleration parameters, inaccordance with the determined time.
 2. The method of claim 1, whereindetecting the group of vehicles includes: determining that all of thevehicles in the group are within a certain distance of the intersection.3. The method of claim 1, wherein detecting the group of vehiclesincludes determining that all of the vehicles in the group are in a samelane.
 4. The method of claim 1, wherein detecting the group of vehiclesfurther includes determining that a distance between each two adjacentvehicles in the group is within a predefined threshold.
 5. The method ofclaim 1, further comprising: monitoring a movement of the group ofvehicles through the intersection, modifying the group in response tovehicles entering or leaving a lane, and adjusting the accelerationparameters in view of the modified group.
 6. The method of claim 1,wherein detecting the group of vehicles includes using at least one of(i) a sensor of at least one of the vehicles in the group, (ii) astationary camera configured to capture images of the intersection, a(iii) a camera operating in an unmanned aerial vehicle (UAV), or (iv)satellite imagery.
 7. The method of claim 1, wherein determining thetime when the state of the traffic light changes includes receiving atraffic light data from a network server that operates the trafficlight, the traffic light data indicative of a current state of thetraffic light and a time when the traffic light is scheduled totransition a different state.
 8. The method of claim 1, whereindetermining the time when the state of the traffic light changesincludes using imagery captured in a camera operating in one of thevehicles in the group.
 9. The method of claim 1, wherein determining theacceleration parameters includes determining a time when the vehicle isto start accelerating and a rate at which the vehicle is to accelerate.10. The method of claim 1, further comprising: monitoring a movement ofthe group of vehicles through the intersection, adjusting theacceleration parameters in view of the movement of the group ofvehicles, and providing updated guidance to the device operated by thedriver, the updated guidance related to the adjusted accelerationparameters.
 11. The method of claim 1, further comprising: determining arespective make and model of each vehicle in the group, and determiningthe acceleration parameters for the certain vehicle in the group in viewof the makes and models of the other vehicles in the group.
 12. Themethod of claim 1, further comprising: determining that at least some ofthe vehicles in the group are turning at the intersection, anddetermining the acceleration parameters for the certain vehicle in thegroup to prevent the vehicle from exceeding a threshold speed forturning.
 13. The method of claim 1, further comprising: determining thatat least some of the vehicles in the group are making a U-turn at theintersection, and determining the acceleration parameters for thecertain vehicle in the group to prevent the vehicle from exceeding athreshold speed for a U-turn maneuver.
 14. The method of claim 1,wherein providing the guidance to the device operated by the driverincludes generating a vocalized instruction to be played back via aspeaker of the device or a head unit of the vehicle.
 15. The method ofclaim 1, wherein providing the guidance to the device operated by thedriver includes providing a navigation instruction in advance of thetraffic light changing to green.
 16. The method of claim 1, whereinproviding the guidance to the device operated by the driver includesproviding a navigation instruction in response to the traffic lightchanging to green.
 17. A portable computing device comprising: one ormore processors; a short-range communication interface tocommunicatively couple the portable computing device to a vehicle; along-range communication interface to communicatively couple theportable computing device to a vehicle; and a non-transitorycomputer-readable medium storing thereon instructions that, whenexecuted by the one or more processors, cause the portable computingdevice to: detect a group of two or more vehicles stopped at anintersection regulated by a traffic light, wherein for each of thevehicles in the group, movement through the intersection in response toa change in a state of the traffic light is affected by movement of atleast one other vehicle in the group, determine a time when the state ofthe traffic light changes to allow the group of vehicles to start movingthrough the intersection, determine one or more acceleration parametersfor a certain vehicle in the group in view of potential and/or actualmovement of the other vehicles in the group through the intersection,and provide guidance to the portable device operated by a driver of thecertain vehicle regarding the determined one or more accelerationparameters, in accordance with the determined time.
 18. A network servercomprising: one or more computing devices; and a non-transitorycomputer-readable medium storing thereon instructions that, whenexecuted by the one or more computing devices, cause the network serverto: detect a group of two or more vehicles stopped at an intersectionregulated by a traffic light, wherein for each of the vehicles in thegroup, movement through the intersection in response to a change in astate of the traffic light is affected by movement of at least one othervehicle in the group, determine a time when the state of the trafficlight changes to allow the group of vehicles to start moving through theintersection, determine one or more acceleration parameters for acertain vehicle in the group in view of potential and/or actual movementof the other vehicles in the group through the intersection, and provideguidance to a device operated by a driver of the certain vehicleregarding the determined one or more acceleration parameters, inaccordance with the determined time.
 19. (canceled)
 20. The portablecomputing device of claim 17, wherein the instructions cause theportable computing device to: monitor a movement of the group ofvehicles through the intersection; modify the group in response tovehicles entering or leaving a lane, and adjust the accelerationparameters in view of the modified group.
 21. The portable computingdevice of claim 17, wherein the instructions cause the portablecomputing device to: determine a respective make and model of eachvehicle in the group, and determine the acceleration parameters for thecertain vehicle in the group in view of the makes and models of theother vehicles in the group